It is characterized by problems paying attention, excessive activity, or difficulty controlling behavior which is not appropriate for a person's age. In children, problems paying attention may result in poor school performance.
Although it causes impairment, particularly in modern society, many children have a good attention span for tasks they find interesting.
Despite being the most commonly studied and diagnosed mental disorder in children and adolescents, the cause is unknown in the majority of cases.
Additionally, an estimated 4.4% of adults have ADHD in the US. When applied to the full US adult population aged 18 and over, approximately 10.5 million adults are estimated to have ADHD in the US. Only a qualified health care professional can accurately diagnose ADHD.